Interaction between p53 and p16 expressed by adenoviral vectors in human malignant glioma cell lines
Seung-Ki Kim1, Kyu-Chang Wang, Byung-Kyu Cho
1Department of Neurosurgery, Seoul National University, College of Medicine, Korea.
Object:
Multiple gene replacements have been examined as a potential treatment modality for malignant gliomas. Nevertheless, no reports are available that detail the synergy, additivity, or antagonism of multiple genes. The aim of this study was to assess the interaction between p53 and p16 genes in the growth of glioma cell lines.
Methods:
The human glioma cell lines U87MG and U373MG were transduced using an adenoviral vector with Ad-p53, Ad-p16, or both. Western blotting was performed to determine the expression of the protein products of the transduced p53 and p16 genes. To establish whether the combination of Ad-p53 and Ad-p16 would be beneficial, the effects of gene combinations at the median inhibitory concentration level were analyzed using the isobologram method. Annexin assays and cell cycle analyses were performed on the transduced cells. Western blotting demonstrated the expression of p53 and p16 in transduced cells. Simultaneous exposure to Ad-p53 and Ad-p16 produced additive effects in both glioma cell lines. Experimental data points in U373MG lay near the Mode I line, indicating that the vectors had a different mode of action. The restoration of normal p53-encoded protein in the mutant cell lines induced apoptosis, whereas in the wild-type p53 cell lines, the overexpression of wild-type p53 resulted in a moderate degree of apoptosis and G1 arrest. Furthermore, Ad-p16 induced more marked G1 arrest than Ad-p53 in cells with wild-type p53.
Conclusions:
The results show that interaction between Ad-p53 and Ad-p16 is additive, regardless of p53 gene status.
Insights
The combination of p53 and p16 gene therapy shows additive effects in glioma cells, offering a potential strategy for malignant glioma treatment regardless of p53 status.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- Malignant gliomas are aggressive brain tumors with limited treatment options.
- Gene replacement therapy is being explored, but the interactions between multiple therapeutic genes are not well understood.
- Understanding gene interactions is crucial for developing effective combination therapies.
Purpose of the Study:
- To investigate the interaction between the p53 and p16 genes in human glioma cell lines.
- To determine if combining Ad-p53 and Ad-p16 gene therapy has synergistic, additive, or antagonistic effects on glioma cell growth.
- To assess the impact of these gene combinations on apoptosis and cell cycle progression.
Main Methods:
- Human glioma cell lines (U87MG, U373MG) were transduced with adenoviral vectors carrying p53 (Ad-p53), p16 (Ad-p16), or both.
- Western blotting confirmed protein expression of p53 and p16.
- The isobologram method analyzed combination effects at median inhibitory concentrations.
- Annexin assays and cell cycle analysis evaluated apoptosis and cell cycle arrest.
Main Results:
- Both Ad-p53 and Ad-p16 were successfully expressed in glioma cells.
- Simultaneous delivery of Ad-p53 and Ad-p16 demonstrated additive effects on glioma cell growth in both cell lines.
- Restoring wild-type p53 induced apoptosis in mutant cell lines and moderate apoptosis/G1 arrest in wild-type lines.
- Ad-p16 caused more significant G1 arrest than Ad-p53 in wild-type p53 cells.
Conclusions:
- The interaction between Ad-p53 and Ad-p16 gene therapy is additive in glioma cells.
- This additive effect is consistent irrespective of the endogenous p53 gene status.
- Combination gene therapy with p53 and p16 presents a viable approach for malignant glioma treatment.
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